June 6, 2011 -- Ovarian cancer screening does not reduce disease-related deaths among average-risk women, but it does result in an increase in invasive medical procedures and associated harms. That’s according to findings from a large, long-awaited, government-funded trial.

Nearly 80,000 women were enrolled in the ovarian screening arm of the National Cancer Institute’s screening study, presented Saturday at the American Society of Clinical Oncology (ASCO) 2011 Annual Meeting.

Women screened annually and followed for up to 13 years died in similar numbers from ovarian cancer and other causes as women who were not screened.

Ovarian Cancer Screening

Ovarian cancer is among the most deadly malignancies and the fifth leading cause of cancer deaths among women in the United States.

Because symptoms, if they occur, are often attributed to other conditions, most women with ovarian cancer are diagnosed late in the progression of the disease.

If caught early, before the cancer spreads beyond the ovaries, the five-year survival rate for ovarian cancer is more than 90%, compared to only about 30% among patients with advanced disease.

“The hope had been that the screening protocol we used would lead to earlier detection and better survival, but that is not what we found,” says Christine D. Berg, MD, chief of the early detection research group of NCI’s division of cancer prevention.

Screening Included CA-125, Ultrasound

The women in the study had an average risk for cervical cancer and were between the ages of 55 and 74 at enrollment. Half the women received ovarian cancer screening and half did not.

The screening protocol included serum cancer antigen 125 (CA-125) blood testing for six years and transvaginal ultrasound for four years.

CA-125 is routinely used to follow tumor progression in women with ovarian cancer, but its value for screening has long been questioned because levels can rise with many other conditions, including endometriosis, pelvic inflammatory disease, and even menstruation and pregnancy.

Over the follow-up, which ended in late February 2010, ovarian cancer was diagnosed in 212 women in the screening group and 176 women who were not screened.

But there was no significant difference in deaths, with 118 and 100 deaths occurring, respectively, in the screened and non-screened women.

The number of deaths from all causes was also strikingly similar, with 2,924 deaths occurring among the screened women and 2,914 deaths occurring among the women who were not screened.